This invention generally relates to ultrasound imaging of the human anatomy for the purpose of medical diagnosis. In particular, the invention relates to methods and apparatus for imaging moving fluid or tissue (with or without contrast agents) in the human body by transmitting ultrasound waves into the moving fluid or tissue and then detecting ultrasound echoes reflected therefrom.
In U.S. application Ser. No. 09/065,212, entitled xe2x80x9cMethod And Apparatus For Enhanced Flow Imaging In B-Mode Ultrasound,xe2x80x9d filed Apr. 23, 1998, in the names of Richard Chiao et al., assigned to the parent of the assignee of the present application and incorporated by reference into this application, the applicants describe a new technique which allows visualization of flow hemodynamics and tissue motion in B-mode using gray scale data (hereafter xe2x80x9cgray scale flowxe2x80x9d). This modified B-mode technique provides fine resolution and high frame rate imaging by subtracting successive B-mode-like firings (for high resolution) to display changes (motion or flow) over time. However, the large bandwidth and small number of firings compared to color flow imaging limit sensitivity. In addition, signals from static tissue and flow are processed identically and presented using B-mode display, restricting possible image segmentation between stationary and flow regions. This invention addresses such problems and provides a solution.
The preferred embodiment is useful in an ultrasound system which acquires data representing two dimensional images of blood flow and tissue motion using both a gray scale mode of operation and a color flow mode of operation. An image of a subject under study is displayed by combining the data from the gray scale and color flow modes of operation.
More particularly, a plurality of beams of ultrasound waves are transmitted into the subject and echo ultrasound waves are received from the subject in response to the transmitted ultrasound waves. The echo ultrasound waves are converted into corresponding received signals. The transmitting, receiving and converting preferably is accomplished with an ultrasound transducer. The transducer is pulsed a first predetermined number of times along one of the beams in the gray scale mode of operation so that the transducer transmits first ultrasound waves and generates first received signals in response to echo ultrasound waves received in response to the first ultrasound waves. The transducer is pulsed a second predetermined number of times along one of the beams during the color flow mode of operation so that the transducer transmits second ultrasound waves and generates second received signals in response to echo ultrasound waves received in response to the second ultrasound waves. Gray scale flow data and color flow data representing movement of portions of the subject are generated. The data preferably are generated in first and second receive channels, respectively. At least portions of the gray scale flow data and the color flow data are combined, preferably by a processor. An image responsive to the combined data is displayed, preferably by a display device. As a result, movement of portions of the subject are displayed with a color highlighted gray scale image.
Using the foregoing techniques provides increased sensitivity and image differentiation between flow and tissue regions through the addition of color data, while preserving the temporal and resolution benefits of the gray scale data.